Rename HandlerInner::delay_span_bug as HandlerInner::span_delayed_bug.

Because the corresponding `Level` is `DelayedBug` and `span_delayed_bug`
follows the pattern used everywhere else: `span_err`, `span_warning`,
etc.

compiler/rustc_span/src/symbol.rs

@@ -641,7 +641,6 @@ symbols! {
         default_method_body_is_const,
         default_type_parameter_fallback,
         default_type_params,
-        delay_span_bug_from_inside_query,
         deny,
         deprecated,
         deprecated_safe,
@@ -1557,6 +1556,7 @@ symbols! {
         slice_patterns,
         slicing_syntax,
         soft,
+        span_delayed_bug_from_inside_query,
         specialization,
         speed,
         spotlight,